1. Field of the Invention
This invention relates to illuminated footwear, and in particular to footwear in which super-thin lighting elements are incorporated in a strap or in the laces of the footwear. The phrase "super thin lighting element " refers to a lighting element of the type containing a chemical sandwiched between protective layers, such as an electro-or photo-luminescent strip or panel.
2. Discussion of Related Art
Illuminated footwear have been proposed in a number of prior patent documents, including U.S. Pat. Nos. 4,035,630, 4,173,201, 4,216,464, 4,423,539, 4,425,600, 4,438,482, 4,480,293, 4,599,682, and 4,935,851. Such illuminated footwear offers increased nighttime visibility for the wearer, as well as increasing the attractiveness of the footwear. However, in each of the above-mentioned patents, the illumination is provided by incandescent bulbs or light emitting diode arrangements which have a number of disadvantages and therefore limited practicality in the context of footwear, including high power consumption in the case of incandescent lights, and a narrow viewing angle in the case of light emitting diodes, as well as the problem common to all point source or essentially spherical lighting arrangements that, because the intensity of light decreases distance from a point or spherical light source according to the inverse square law. In the case of light sources small enough to be used on footwear, in the absence of reflective materials or fiber optics to carry the light emitted by the source a further distance, the visibility of the lighting elements is limited to about three or four feet. While reflectors, fiber optics and the like are of course available, the use of visibility enhancing means to increase the visibility of LEDs or incandescent lights beyond three or four feet can greatly increase the cost and assembly time for the footwear, and is generally impractical.
To solve this problem, it has also previously been proposed to use super-thin lighting elements to provide illumination for footwear. In addition to increasing the visibility of lighting arrangements utilizing super-thin lighting elements, the super-thin lighting elements offer a number of advantages over conventional lighting elements such as incandescent light bulbs and light emitting diodes, including flexibility, which allows the lighting elements to follow curves on the object to which they are attached, the ability to be printed or silk-screened with logos, marks, figures, and characters, or to be stenciled or masked, the availability of a wide variety of color choices, including green, blue, pink, yellow, and white, and low assembly and design costs.
The advantages of using super-thin lighting elements in a variety of contexts are explained in several pending U.S. patent applications and issued patents of the Inventor. These pending applications, some of which disclose footwear and others of which disclose other types of devices or objects illuminated by super thin lighting elements, in general have in common disclosures of lighting elements which are either applied-directly to the surface of objects and devices, or which are mounted on specially designed brackets or housings. Serial numbers of the pending U.S. patent applications include Ser. Nos. 08/226,322; 08/305,294; 08/343,404; 08/343,915; 08/383,404; 08/383,405; 08/421,647; 08/432,707; 08/438,373; 08/444,064; 08/436,007; and 08/522,940.
The super-thin lighting arrangements described in the above-cited prior applications, as well as in other prior patents, can be manufactured to have a wide variety of forms by using appropriate processes for coating light emitting pigments onto clear or opaque backing materials to emit light from a single side, both sides, or over 360.degree. to form sheets, tubes, bars, cylinders, spheres, and other shapes. Typical electro-luminescent lighting elements, by way of example, are made of multiple layers having a thickness of less than 0.40 cm total for a single-side illuminated surface sheet, with a few additional millimeters required for multi-sided arrangements. The three dimensional elements can easily be made by a vacuum spraying process to get a lighting element which emits light beams at a variety of angles to permit the observer to see the light at any angle.
The present invention utilizes this design flexibility of super-thin lighting elements by applying them in a novel way in the context of footwear. As indicated above, it is known to use electro-luminescent lighting element in the context of footwear, but in general the lighting elements are simply applied to the surface of the footwear, exposing them to damage, or are including in special housings or mounting brackets, which can be inconvenient, and none of the prior patents or applications suggest the basic concept of the present invention, which is to place the lighting elements in lace assemblies or straps in order to take full advantage of the extended surface area of illumination provided by the lighting elements while placing them in a location which offers protection for the lighting elements, eliminates the need for unnecessary hardware such as mounting brackets for the elements, simplifies manufacture of the shoes since the lighting elements do not need to be separately stitched or bonded to the footwear (the elimination of unnecessary manufacturing steps will become apparent from the detailed description), and offers some "discreetness" for daytime use (such that the lighting elements are primarily visible when illuminating after dark). Also, the lighting elements of the invention can be pre-worked or assembled on a side-line and added to the shoe without holding-up or requiring significant changes to the main assembly line.